New research reveals that the virus behind polio disease could have a surprising benefit of effectively combatting a particularly severe form of brain cancer.
Cancer is one of the biggest killers around, so doctors have been desperately looking for a solution. While an actual cure is likely to be years away, researchers say there are promising signs that it may lie in another deadly virus: polio.
The study published in the New England Journal of Medicine found that a safe, engineered version of the poliovirus improves the survival rate of glioblastoma, an aggressive and highly lethal type of brain cancer.
Polio For Brain Cancer
The virus for polio can attach itself to a receptor on glioblastoma cancer cells and of the most solid tumors, which gives the virus the opportunity to attack and kill these cells.
"Our strategy did not start out with the intent to use poliovirus in cancer immunotherapy," co-author Dr. Annick Desjardins of Duke University explains to CNN. "Rather, Dr. [Matthias] Gromeier made a series of research observations over many years."
Desjardins says that Gromeier found that a poliovirus receptor was "virtually universally expressed on cancerous cells of most tumors" except Burkitt's lymphoma.
To make sure the engineered version of poliovirus doesn't cause polio in the patients, the team replaced the genetic sequence allowing it to reproduce in normal cells with the sequence from the common cold virus. The resulting virus is still able to reproduce in cancer cells, releasing a toxin that can destroy the cancer cells.
The Findings
The researchers started with animal experiments, then moved on to treating human glioblastoma patients in 2012. A catheter is implanted in the brain with the engineered poliovirus injected directly into the tumor.
The long-term study saw 21 percent of the participants treated with the experimental poliovirus survive for three or more years. In comparison, only 4 percent survived from the set of patients who opted for standard treatment of chemotherapy sessions.
Overall, the average survival period of patients who received the modified poliovirus was 12.5 months. This is slightly better than the chemotherapy patients who had an average survival period of 11.3 months.
Severe inflammation occurred in some patients who received higher dosages, which led to seizures, cognitive difficulties, nausea, and other side effects.
Future Steps For Treatment
Next, clinical trials will begin on participants with melanoma skin cancer and brain cancer. Since it's especially difficult infusing therapy into the brain, the researchers are expecting better results when applying this treatment to cancer in other parts of the body.
The team is also currently receiving enrollments for phase two trials, which combines the engineered poliovirus with chemotherapy.